How does a rotary kiln burner work?

Most of the burners of the rotary kiln extend into the kiln head barrel through the kiln head cover, and heat the material to the required temperature through flame and radiation. There are many forms of burners, such as coal injection pipes, oil spray guns, gas nozzles, etc., which vary depending on the type of combustion. When the reaction temperature is low, a combustion chamber is set up next to the kiln hood to supply heat to the hot flue gas into the kiln.

In the early rotary kiln, the burner mostly adopts a single air duct structure, the primary air volume accounts for about 20% 30% of the total combustion air volume, and the primary air speed is 40 70m s, its function is mainly to transport pulverized coal, and the effect on coal air mixing and secondary air suction is very small, and the flame is also inconvenient to adjust, and it is difficult to meet the production requirements. With the development of pre-decomposition technology and the increasingly demanding requirements for the use of low-reactive fuels and environmental protection, new progress has been made in burner technology. Various manufacturers have adopted multi-duct burners, which have the following functions;

1) Increase the mixing of pulverized coal and combustion air, increase the combustion rate, and the fuel is completely and stably combusted.

2) Increase the means of adjusting the air volume and wind speed of each channel, so that the flame shape and temperature adjustment are flexible and convenient, and it is suitable for clinker calcination.

3) The burner has a long service life.

4) Protect the inner lining of the kiln and prolong the service life of the inner lining.

5) Stabilize clinker quality and improve system output.

6) The structure is simple, the maintenance and replacement are convenient, and the system operation time is reduced due to burner failure.

7) Try to reduce the amount of primary air, increase the utilization of high temperature secondary air, and improve the utilization rate of clinker heat.

8) The system resistance is as low as possible to reduce the energy consumption of the primary fan.

9) It can reduce the emission of harmful substances (especially NOx) the most.

10) Low-grade fuel can be used, the comprehensive utilization of fuel can be strengthened, and the equipment and maintenance costs are lower.

The flame temperature of the burner part is above 1800, which is affected by fuel combustion, and the temperature changes frequently and the temperature difference is large. The burner lining is subject to the radiation of more than 1400 high-temperature clinker and the serious erosion and erosion of clinker dust, as well as the chemical attack of the sticky fine-grained clinker and alkali sulfur compounds contained in the high-temperature flue gas.

The working principle of the rotary kiln burner, open the controller, open the solenoid valve after the power is on, the pipeline is gased, and then the ignition electrode is ignited in turn according to the energizing order, and the gas or fuel oil is atomized (oil) through the burner mouth and then the flame is sprayed out through the fan plate to achieve the heat required by the rotary kiln.

Rotary kiln is an important clinker production equipment, which is widely used in cement, metallurgy, chemical industry and environmental protection industries. It works by putting raw materials into a rotary kiln, which is rotated at high temperature to complete the chemical reaction and finally obtain the desired finished product.

The rotary kiln is mainly composed of a cylinder, a transmission device, a support device and a combustion equipment. When the fuel is ignited, the high-temperature flame transfers heat to the cylinder, and Chunchun forms an extremely high temperature within the cylinder. The raw material and the gas interact in the rotary kiln, and this process is known as the drying and preheating stage.

In this process, the raw material gradually dries out on the side of the cylinder close to the heat source, while it also heats up gradually through heat conduction. This stage usually takes a long time, and the combustion of the fuel tends to continue the entire process.

When the raw material is dried and preheated, it enters the hot area inside the kiln. During this process, the high-temperature gas will flow down the barrel. The raw material is chemically recycled and then matured, and finally cooled in the cooling area before being exported.

The overall time of this process and the temperature of the high temperature area directly determine the yield and quality of the clinker.

Overall, a rotary kiln is a very complex and important piece of equipment that needs to be controlled from several aspects. For example, it is necessary to control the speed and stability of the fuel feed, as well as the speed and temperature of the entire plant. Real-time monitoring and adjustment with the right control technology is also required to ensure that both the quality and yield of the clinker meet the requirements.

Cement firing equipment includes shaft kiln, wet rotary kiln (rotary kiln), ordinary hollow dry kiln, Libo kiln, preheating machine kiln (SP) and the new dry rotary kiln (rotary kiln) commonly used at present.

Rotary kiln (rotary kiln) is a cylindrical with a certain inclination, the inclination is 3, with the help of the rotation of the kiln to promote the material to stir in the rotary kiln (rotary kiln), so that the material is mixed with each other, contact and react. Coal injection combustion at the kiln head produces a large amount of heat, and the heat is transmitted to the material by the radiation of the flame, the convection of hot gas, and the conduction of kiln bricks (kiln skin). The material moves forward in the kiln by the slope of the kiln cylinder and the rotation of the kiln.

1) On the one hand, the rotary kiln (rotary kiln) is a combustion equipment, in which pulverized coal is burned to produce heat; At the same time, it is also a heat transfer equipment, and the raw material absorbs the heat of the gas for calcination. In addition, sometimes conveying equipment conveys raw materials from the infeed end to the discharge end. The fuel combustion, heat transfer and raw material movement must be reasonably coordinated, so that the heat generated by fuel combustion can be transmitted to the raw materials in time when the raw materials pass through the rotary kiln (rotary kiln), and the purpose of high yield, high quality and low consumption has been achieved.

2) The movement of raw material particles in the rotary kiln (rotary kiln) is more complicated. If it is assumed that there is no sliding phenomenon of raw material particles on the kiln wall and inside the raw material layer, it is generally believed that the movement of raw materials is like this: the raw materials slowly rise as a whole together with the kiln wall under the action of friction, and when they turn to a certain height, that is, when the angle formed between the surface of the raw material layer and the horizontal plane is equal to the accumulation angle of the raw materials, the raw material particles slide down along the material layer under the action of gravity.

Since the rotary kiln (rotary kiln) has a certain inclination, and when the raw material particles roll, they fall in the direction of the maximum slope, so they move forward a certain distance.

When the raw material moves in the kiln, the movement mode of the raw material particles changes periodically, or it is buried in the material layer and moves up with the kiln, or it falls down on the surface of the material layer. But it is only in the process of the raw material particles falling along the surface layer that it can advance in the direction of the kiln length.

The movement of raw materials in the kiln will affect the residence time of raw materials in the kiln (i.e. the heating time of raw materials); the filling coefficient of the raw material in the kiln (i.e., the heated area of the raw material); The rotation of the particle size of the raw material also affects the uniformity of the raw material (i.e., it affects the surface temperature of the combustion product and the raw material).

Attention must be paid to the influence of various motion conditions on the center angle, i.e. on the filling coefficient of the raw material particles. If you want to maintain a certain filling coefficient in the kiln, it is necessary to make the kiln speed and feeding speed cooperate with each other and maintain a certain proportion; This is also the process conditions to improve yield, quality, stabilize the thermal system, overcome agglomeration, etc.

A preheater and a cooler are two different things. The rotary kiln preheater is composed of three parts, each of which has different functions. The cyclone mainly plays the role of gas material separation, and also has a small amount (about 20%) gas and material heat exchange; The connecting pipeline mainly plays the role of heat exchange of gas material (about 80%), and the air lock valve (that is, the ash discharge valve) as the name suggests, its role is to lock the air to prevent the wind from short circuit through, and a ash discharge, so that the raw meal can smoothly enter the next cyclone.

A cooler is a device used to cool clinker.

First of all, the preheating is a device outside the kiln tail, and the cooling is another device outside the kiln head, and the preheater is a heat exchange device, so that the temperature of the exhaust gas drops rapidly, and the temperature of the raw meal rises rapidly, so as to reduce heat consumption, improve the quality of production, save energy, and make comprehensive utilization.

For example, the suspension preheater is characterized by the heat exchange between the dry raw meal and the hot gas in the rotary kiln in a suspended state. In the suspension preheater, the raw meal is evenly dispersed in the air flow, and the surface of the raw meal particles is directly in contact with the hot air flow, the heat exchange area is very large, and the heat transfer effect is good. And, because the raw pellets are small, heat is quickly transferred from the surface to the center.

As a result, the heat transfer rate is also extremely fast, and the raw meal can be increased from room temperature to more than 750 C in a few tens of seconds. Since the suspension preheater is a highly efficient heat exchanger, the heat consumption of this kiln type is very low, only 3140 3560 kJ kg clinker.

We Henan Nanyang Kiln Mining specializes in the production of rotary kilns, preheaters, coolers, crushers, dryers, welcome you to come to buy and negotiate.

1. The rotary kiln is composed of a cylinder, a shed gear wheel belt, a supporting wheel, a retaining wheel, a transmission device, a sealing device, a cooling device (multi-cylinder cooler, etc.), and the cylinder is welded with a brick retaining ring, a refractory brick, and a retaining ring at the cold end; The inner cold end of the wet rotary kiln is also hung with chains and other metal heat exchange devices or slurry evaporators; The end of the Libo rotary kiln is equipped with a grate heating machine; The suspension preheater rotary kiln tail is provided with a suspension preheating device; The vertical cylinder preheater rotary kiln is also equipped with a blanking tongue in the kiln, and other limb rotary kiln types are also equipped with a blanking device.

2. There is a manhole door on the cylinder, and a reinforcing ring is welded to increase the rigidity of the kiln body, the hot end of the kiln is connected to see the fire cover, the kiln head is equipped with pulverized coal combustion calendar and positive device, and the cold end is connected with the smoke chamber.

3. The rotary kiln is a cement clinker calciner that integrates multiple functions of combustion, heat transfer, mixing, reaction heat storage and transportation.

The steelmaking furnace is vertical, the top is fed and coal, and the bottom is discharged, the product is a molten high-temperature fluid, and the discharge method should be intermittent;

The cement rotary kiln is lying type, there is a certain height difference, constantly rotating at low speed in one direction, the coal is sprayed in the form of pulverized coal from the low end, combusted, the powder is preheated by the preheater, the decomposition furnace is decomposed, and the high end of the rotary kiln is added, under the action of height difference and low-speed rotation, it slowly moves to the other end, and the temperature gradually rises (up to 1400-1500 degrees), forming a high-temperature micro-melting solid clinker mineral, which is continuously discharged at the low end of the rotary kiln. Of course, the discharged high-temperature materials are preheated, just like the steelmaking furnace. Above the high end of the rotary kiln, there is a decomposition furnace (800-850 degrees) and several stages of preheater, which play the role of preheating raw materials and decomposing carbonates.

1. The burner of the rotary kiln of large and medium-sized plants should adopt a multi-channel burner with an oil-injected ignition device, and a set of oil supply system for burner ignition. The length and angle of the burner should be adjustable, and it is advisable to use a hanging or support fix.

2. The burner of the rotary kiln should be determined according to the kiln type and coal quality. The multi-channel burner is the most advanced pulverized coal burner in the world and widely used in rotary kilns. It is characterized by:

The primary air volume is small, the shape and length of the flame can be flexibly adjusted, and the coal quality and fineness of different ash are adaptable, especially in the case of high ash content, so that it can achieve complete combustion, so as to not only better adapt to the complex and changeable combustion conditions, improve the combustion efficiency, but also have a more obvious effect on reducing energy consumption.

3. The proportion of the primary air volume of the multi-channel pulverized coal burner to the theoretical air demand should not be more than 15%;

4. The primary fan should be equipped with an accident fan or a standby fan.

1.Its technical performance and Yunzhou blind turn, to a large extent, determine the quality of the company's products, output and finished potatoes. The ballad "As long as the kiln turns, there are thousands" is a vivid description of the importance of the rotary kiln in production.

2.In the building materials industry, in addition to calcining cement clinker, rotary kilns are also used to calcinate clay, limestone and slag drying; In the production of refractory materials, rotary kilns are used to calcinate raw materials to make them stable in size and increase in strength, and then processed and formed.

3.In the process of beneficiation, the rotary kiln is used to magnetize and roast the poor iron ore, so that the original weak magnetism of the ore is changed to strong magnetism, which is conducive to magnetic separation.

This method has the advantages of low energy consumption, low electricity consumption, no sulfuric acid and the use of medium and low-grade phosphate rock.

5.The whole production process of cement is summarized as "two grinding and one burning", in which "one burning" is the process of burning the raw meal prepared by grinding into clinker under the action of high temperature of the rotary kiln. Therefore, the rotary kiln is the main engine in cement production, commonly known as the "heart" of the cement plant.

6.In terms of environmental protection, the developed countries in the world have used cement kilns to incinerate hazardous wastes and garbage for more than 20 years, which not only reduces and harmlessizes waste, but also uses waste as fuel, saves pulverized coal, and achieves waste recycling.